1. Field of the Invention
This invention broadly relates to inspection devices and related fixtures, and deals more particularly with an apparatus for transporting and positioning an inspection device within a walled cavity, such as inside an aircraft wing.
2. Description of the Related Art
A wide variety of new technologies are now employed to detect defects and measure or verify structural features within closed volumes or cavities in large and bulky manufactured items. For example, aircraft wings may be constructed using multi-spar internal boxes formed of co-cured composite materials. These wing boxes have walls defining long cavities which may be 40 or more feet in length. In some cases, the cross section of the cavity may change in dimensions and/or directions along its length. For example, the cavity within a horizontal stabilizer box may taper from approximately 2 feet in cross section to 6 or 7 inches over a 40 foot length.
In the context of the aircraft industry, features of a stabilizer box requiring inspection or verification include internal dimensions, the position of radius corners, the location of holes used for fasteners and similar structural features that are critical for quality or assembly. In order to inspect and measure these features, verification technologies including cameras, laser line measurement, laser dot scanning, and other nondestructive inspection techniques are used.
A problem may arise, for example, in gaining access to locations within the horizontal stabilizer box along its length using the selected verification equipment. Gaining inspection access is compounded by the fact that it is often necessary to position the verification equipment within the stabilizer box cavity, and then maintain this position as the equipment is moved along the length of the cavity. For example, some measurement devices must be precisely positioned in the corners of the cavity along its length, while other measurement equipment such as a laser scanner and cameras need to be located at the center of the cavity, even when the cavity changes cross sectional dimensions along its length.
Transport mechanisms have been developed that are capable of carrying inspection equipment through a large cavity. For the most part, these cavities are well ordered geometries such as circular pipes or square tubes. However known mechanisms may be ineffective in centering or precisely positioning inspection equipment within a cavity that is not well ordered such as a tapering rectangle or rhombic geometry. Moreover, while known camera inspection systems are used to image features in remote areas within the cavity, these systems cannot accommodate drastic changes in cross sectional dimensions of the cavity as its length is traversed. Similarly, these prior inspection systems may not be able to move around partial barriers that may be encountered within the cavity, such as bulkheads or spars.
Accordingly, there is a need for a system for transporting and positioning inspection and measuring equipment within cavities that avoid the problem discussed above. The invention is directed towards satisfying this need.